To use the Nano, it is no problem that the IP5303 switches off after 35 seconds when switching off. For a battery pack with a low consumption device connected, that is something else.
The problem that I often hear is that the IP5303 does not switch on, with a consumption higher than 45 mA. I have already replaced and restored just about everything around the IP5303, but that doesn't help. The normal functions continue to work, only the start-up does not work.
The only solution is to start the IP5303 via the key pin 5 with a push button. This is only a partial solution, because after connecting the USB cable it no longer works.
After several days of measuring and testing, and 2x replacing an IP5303, I finally found a deviation. All measurements of the NanoVNA power consumption described here are actually wrong. You will not find any deviations.
However, if you are going to measure the power consumption of the IP5303 yourself, we will notice weird deviations.
The third day I planned to do only current measurements on the IP5306 and its components.
Like 'tinhead' suggested to place a resistor on C47, instead of a resistor I made a print with 4 lamps 6V / 60mA, and a 4-pole DIP switch.
This way I could switch the load per 60 mA on and off to observe the behavior of the IP5306.
Since the NanoVNA does not participate this time, the current must be measured at the 3.70V battery and not at the ON / OFF switch.
These prior measurements gave strange results:
Current measurement of the IP5303 in standby mode (32 sec): 2.70 mA
Current measurement of the NanoVNA, including the IP5303: 237mA!
Current measurement of the NanoVNA, minus the IP5303: 130mA.
Conclusion: the IP5303 has (too) high self-consumption.
I discovered that the IP5303 only worked well up to 222 mA. In addition, the IP5303 goes into a kind of protection mode, and switches off completely after about 10 seconds.
The following measurements are with my own load (lamps), without the Nano switched on.
With my external load I can therefore switch on 1,2,3 or 4 lamps.
1 lamp = 60 mA, 2 lamps = 120 mA, 3 lamps = 180 mA, 4 lamps = 240 mA.
With the standard inductor of 2.2 ?H (1 ?H also works, but the oscillator frequency is higher) and a load with:
1 lamp: current was 90.0 mA -> 30 mA too much
2 lights: current was 185 mA -> 65 mA too much!
3 lights: current was 276 mA -> 36 mA too much!
The load with 4 lamps did not want to start anymore.
This is really too much for the small Li-ion battery.
Strange is that the IP5303 with my own load did not fail, with the NanoVNA switched on it did fail.
So the ultimate consequence is that the NanoVNA does not want to start up, because it itself already needs 130 mA.
I did the same measurements again with a lab power supply connected instead of the battery, but the measurements were not much different.
The question is why the IP5303 does not meet its specifications.
There are probably some IPs that do not work well in some NanoVNAs.
Or some NanoVNAs have a slightly lower power consumption. I replaced the IP5303 twice, I was not lucky twice.
I'm still going to try with an IP5306, which could handle a slightly higher steam. But they still have to be ordered.
